Authorities are watching towns in the north-east, as the Macquarie and South Esk Rivers rise faster than expected.

The State Emergency Service says residents are not in any immediate danger.

Floodwaters continue to block roads and bridges, as emergency crews prepare for rivers to peak.

The run off from heavy rain earlier this week is surging down the South Esk River which has peaked at eight metres at Perth.

The weather bureau says it is the biggest flood in Perth for 15 years.

Woolmers Road at Longford and Leighlands Road in Evandale have been closed this morning due to flooding.

The Glen Esk Bridge is under water, and the Powranna Road is also flooded.

Hydrologist Chris MacGeorge says water in the South Esk and Macquarie Rivers will remain high for some time.

"We basically have those two river systems expecting to peak at Longford today, and probably staying high for the next 24 hours."

Mr MacGeorge says it now appears as though it is the biggest flood on record for Perth in 50 years.

"December '93 it was around about 7.4 metres, so it's definitely exceeded that," he said.

"The last big one was about 8.1 was about 1958, so it's certainly been a long time between drinks for that kind of level."

"At Longford itself we're probably looking up to the five and six metre mark, which is quite significant for them because the holes in the levee system are probably at that mark." he said

While rain has eased, rising flood levels in rivers is expected to peak early this afternoon.

The general manager of the Northern Midlands Council, Mark Pitt has told ABC Local Radio that they are well prepared for the flood threat.

"Most people that live along the river are fairly well atuned to the river and what it's doing and actually."

"I got some good information as far as the movement of the river from them and I'm quite confident, as much as you can be in these sorts of things, but the level of preparedness is there and we're ready to go and do whatevers necessary."

This morning police went to the aid of a motorist who was stranded in flood waters on the Perth Mill Road.

Mhairi Vogt from the State Emergency Service says evacuations will not be necessary but residents need to be careful.

"We're keeping a close on the Perth Cressy Longford and Campbell Town areas, while the residents of those areas don't need to worry about evacuations they need to be on the lookout for water over bridges and rivers."

"We would expect that there would be a lot of bridges and roads under water," she said.

Flooding on the east coast is now starting to ease but St Marys Pass remains closed due to a rock fall.

Binalong Bay and Ansons Bay roads are also still closed due to flooding, as well as the Glen Esk road at Conara and the Storeys Creek road at Avoca.